An earthquake in Kobe speaks to a sea wall in San Francisco
At 5:46 a.m. on Jan. 17, 1995, a security camera inside a convenience store in Kobe recorded as a cashier plucked change from the register and passed it across the counter to a customer, who, coins in one hand, plastic bag in the other, turned toward the shop door. In that instant, the entire store lurched, shoving everything in it toward the wall behind the register. The two men sank to their knees, caught in a circular shaking motion that sent shelves sliding and tipping, hurling boxes and any loose items to the floor, and slamming the front doors open and shut.
Down at the waterfront port, which is spread across several artificial islands, the land moved like water, rippling in the seismic waves. Concrete quays collapsed into Osaka Bay. These structures built to keep water out no longer did.
Seismographs quickly confirmed: A magnitude 6.9 earthquake had paralyzed the entire city. Bridges and highways were ruined; water, electricity, and telecommunication lines were cut off. Hundreds of thousands of people lost their homes. Over 6,000 people died. Restoration work endured for years.
Today, researchers worldwide view Kobe as an example of a modern city where structures failed to perform the way engineers thought they would.
Halfway around the world another metropolis — San Francisco — has drawn worrisome parallels: Like Kobe, the Northern California coastal city sits at the heart of a dense, seismically active urban area constructed on enormous areas of filled land, much of which is protected by a sea wall vulnerable to the rising waters caused by climate change.
Its particular confluence of geology, city construction and overdue infrastructure updates feeds into its vulnerability, but other cities around the world, too, face the twin challenges of seismic hazards and rising seas, from Jakarta to Christchurch, New Zealand, and any city along the coastline of the Pacific Ocean from Alaska in North America to Patagonia in South America.
While each locale must find solutions suited to its individual circumstances, the premise remains the same: Time is running short to fortify infrastructure built in a world that did not account for climate change. Wealthier countries will have better odds of succeeding. Nonetheless, the challenge for all becomes how cities secure themselves against disaster today while also anticipating future adjustment and adaptation.
San Francisco is a microcosm of some of the challenges lurking around the globe. And while the city is making some progress in fortifying its protective sea wall, the question is: Are the plans unfolding fast enough? Are they ambitious enough?
Researchers from the U.S. Geological Survey say San Francisco has a 72% chance of at least a magnitude 6.7 quake’s occurring before 2043, and it could come as early as tomorrow. At levels like that, Port of San Francisco engineers calculate that the city’s underwater sea wall, a 19th-century pile of rocks and concrete that holds the northeast waterfront in place, is likely to slide into San Francisco Bay. The result: a catastrophic unhemming of a city of nearly 900,000 people. That the wall has already sunk into the bay makes future risk that much more foreseeable.
In an earthquake over 7.0 in magnitude and with an epicenter within 16 kilometers of San Francisco, the Embarcadero roadway, which on a typical day hosts around 94,000 vehicle passenger trips, is predicted to split. Along this thoroughfare, bookended by views of the city’s two bridges, lies the West Coast’s key financial district on one side, and the historic waterfront that welcomes over 15 million visitors each year on the other.
About 300,000 tourists arrive through its international cruise terminal each year, and as many as 48,000 regional commuters pass through the Embarcadero BART station each weekday. It’s a central channel for utilities that keep the city in motion, from water to sewer lines, electrical to natural gas conduits.
During one of the most worrisome earthquake scenarios, described in Waterfront Resilience Program documents, when the ground spills into the bay, engineers fear that so, too, might the utility corridor, rupturing pipes and electricity lines. The historic pier sheds and bulkhead wharves would tumble into the water, and the wooden piles supporting them would splinter. Researchers predict that the land supporting near-shore blocks of the city — former marshland — will convulse like water just as in Kobe during the Great Hanshin Earthquake, displacing anything and anyone atop it.
If the quake hits on a weekday, 40,000 people could be along the waterfront, many stuck in collapsed structures or piers over water. This same area, along the Embarcadero, holds the city’s disaster response services, including evacuation facilities and its emergency operation center, which would be cut off when most needed. Over $100 billion in building value and economic value are potentially at risk from sea wall collapse, not including pricey utility repair. Port engineers fear much of the sea wall itself would be irreparable.
The Port of San Francisco (which manages 12 km of the city’s waterfront, including nearly 5 km buttressed by the sea wall) had assumed the wall needed upgrading, but it did not know just how direly until 2016, when officials released a preliminary study of the seismic vulnerabilities. Unlike some sea walls, San Francisco’s provides structural support as well as flood protection. The subsequent 2020 report detailed its weak points on both fronts.
As climate change makes ocean levels rise, the sea wall will increasingly have to perform in a context it was not designed for. Given that an earthquake could strike any day, the port’s immediate priority is ensuring the sea wall’s integrity in such an event. But doing so also must consider sea level rise, and its uncertainties of how fast and how high. Risk mitigation decisions made now must allow for the unknowable.
Patrick King, who directs port and maritime work at Jacobs, the engineering firm managing the port’s resiliency program, articulates the urgent challenge of designing a future waterfront. “This infrastructure was built for a certain environment that no longer exists and is rapidly changing,” he said. And now, to the best of their ability, “We need to predict what that environment is going to look like.”
“Wall” is a generous word for the pile of rocks sitting on top of mud running along San Francisco’s northeastern waterfront. During the feverish early days of the gold rush, San Franciscans built the sea wall in a slapdash effort to establish some flat land at the edge of the hilly city. Horses were struggling to lug gold-filled wagons over the hills, and San Franciscans needed warehouses and counting-houses on level ground. Impatient for steam-powered shovels to arrive from across the country, residents began dumping into the marshland of Yerba Buena Cove whatever was on hand: loose sand, debris remnant from city construction, unwanted goods, trash, remains of abandoned ships. After a year, San Francisco had expanded three blocks into the Bay.
To rein in the construction chaos, the California Legislature established a Board of State Harbor Commissioners to create a harbor development plan. Construction of their first sea wall — essentially a rescue mission for the trashed harbor — began in 1867. A better-funded effort took off in 1878, and construction continued in stages over the next four decades.
Though longevity was not at the forefront of the undertaking, the wall still stands — long outlasting what anyone could have expected. And to some experts, this is worrisome.
“I would suggest that San Francisco has triple jeopardy,” King said: earthquakes, sea level rise and aged infrastructure.
Until now, the wall has mostly worked, though barely. In the 1906 earthquake, the sea wall shifted into the bay, crumpling streetcar tracks, rupturing pipes and destroying homes. Entire stretches of street slid sideways; other portions dropped a couple of feet. In today’s city, a similar disaster would be even worse.
In 1989, the magnitude 6.9 Loma Prieta earthquake liquefied sections of soil, most notably in the Marina District, where terrible fires broke out. Along the Embarcadero, the sea wall cracked. Some of its construction joints split open.
“We had a huge fissure out here,” recalled Mac Leibert, 51, general manager of Pier 23 Cafe Restaurant & Bar, gesturing to the Embarcadero roadway outside of the squat blue-and-white cafe.
The epicenter of Loma Prieta was 100 kilometers southeast of San Francisco. The effects of its shaking in the city were tempered by its distance. Next time, San Francisco might not be so lucky.
Despite impending bleak scenarios, steps to a safer, more secure future along the waterfront have started to become visible. Ahead lies the difficult work of balancing design solutions, an unknown future and budget constraints — all against the backdrop of the fast-ticking clock.
Seismically shoring up the sea wall is first on the port’s list of projects. This means retrofitting bulkhead wharves and walls by reinforcing piles, joints, and decks, and strengthening the fill so it will not liquefy. It also involves working with emergency medical workers and emergency responders to understand how their capabilities might be affected by an earthquake.
Right now, the port is in “the creative phase,” developing its first adaptation plans, which will be revealed in the fall. The measures will not be restricted to seismic risks. According to the port’s Waterfront Resilience Program director, Brad Benson, “It’s better to build once to solve multiple problems.”
Making seismically fortified structures resilient to rising seas is not as simple as raising the wall’s height. Generally speaking, most sea wall infrastructure has, until now, been designed to weather an isolated storm, allowing time to repair before the next one. Going forward, sea walls will need to provide protection not just several days a year, but twice daily, at increasingly elevated high tides. Infrastructure design will have to account for this increased stress, and even more so in seismic zones, says Mark Stacey, an engineering professor at the University of California, Berkeley.
“The seismic aspect has to be really robust, and probably some redundancies or over design,” he explained. “Because earthquakes will coincide with those flood protection systems being active.”
While much of the San Francisco Bay is suited to marshes or other green infrastructure as flood control, the Embarcadero nearshore waters are generally too deep for such strategies. Certain ecological interventions, like a textured sea wall to encourage marine life, could provide critical habitat but will not benefit seismic or flooding mitigation strategies.
However structures are seismically strengthened, the ability to adjust them will be built in. Because the sea wall material, the mud and fill underneath, and the infrastructure adjacent vary along the waterfront, so will strengthening and adaptation techniques. “It can’t just be, let’s elevate 3 feet so that we can’t flood in this particular area,” King said. “It’s got to be, what is the future state of this environment, and what is the population going to need? You have to build in the adaptive capacity to change as the environment changes.”
The San Francisco Bay Conservation and Development Commission recently permitted a levee upgrade project in nearby Foster City that exemplifies how adaptation over time could play out. Every five years, the city will evaluate the physical structures and updated federal and regional guidance. If necessary, it will perform a new risk assessment, potentially adjusting structures.
The looming question over any discussion is how to pay for these projects. The sea wall project is estimated at $5 billion, and it is only one of many port projects addressing waterfront resiliency. But it is a price tag that will be paid over 30 years, and funding options look better now than they have recently. The successes of public-private partnerships in existing waterfront projects bode well for future work. California’s state budget surplus just yielded a proposed $11.8 billion to address climate risks, with $211.5 million allocated to coastal resiliency. The administration of U.S. President Joe Biden recently announced expanding the Federal Emergency Management Agency’s Building Resilient Infrastructure and Communities program, which provides pre-emptive hazard mitigation funding.
All these options are positive developments in the United States, where funding is typically not allocated until after the disaster: Think of the FEMA and HUD money after Hurricanes Katrina and Sandy. “This really separates us from other places, doing upfront planning,” said Brian Strong, San Francisco’s capital planning director and chief resilience officer. “It’s very hard to get the money before the disaster happens, to be proactive about it.”
Strong’s remarks come just months after his city weathered other simultaneous disasters: COVID-19, noxious air quality, extreme heat. The surplus budget enabling climate funding happened in part because the pandemic did not sink the economy as severely as projected. According to California Assembly member Al Muratsuchi, chair of the Joint Legislative Committee on Climate Change Policies, now could be “a once-in-a-lifetime opportunity” to invest in climate crisis preparedness.
After shepherding his city through the challenges of the past year and culling lessons about disaster response along the way, Strong is sanguine, if sober, about San Francisco’s ability to be prepared for what comes next.
“We really don’t have a choice,” he says. “It’s impossible to solve everything in a few years. We’re taking a long-term view.”
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